Reactive systems may be composed of a number of concurrent processes and network distributed services, where interruptions in a flow of execution can occur at any time. These systems are very difficult to test. One of the reasons is that the possible number of combinations of allowed interruptions at different points of a flow of execution is huge. This makes exhaustive specification of each possibility infeasible. Without a specification, automated test case generation and selection is compromised. This work presents a strategy for testing interruptions in reactive systems that covers modelling (devoted to testing) of systems with interruptions, generation and selection of sound test cases. The strategy is supported by the LTS-BT tool. A case study is presented to illustrate its applicability in the mobile phone application domain.